The vulnerability is a regression which in some cases caused frequent crashes. Users running the HTML Validator add-on were particularly affected, although other users also experienced the crashes. The problem was due to memory corruption, similar to problems identified as security vulnerabilities in the past.

More details about the release can be found in the release notes. Firefox 3.0.10 is available to download, or Firefox users can use the Firefox update service by selecting Help, then Check For Updates.